Process for the production of crimped acrylonitrile base yarns with an isopropanol containing bath

ABSTRACT

A PROCESS FO PRODUCING SYNTHETIC YARNS AND FIBERS CONTAINING AT LEAST 50% ACRYLONITRILE COMPRISING: SPINNING AN ACRYLONITRILE POLYMER BASE SLUTION INTO A COAGULANT BATH COMPRISING A SOLVENT FOR THE ACRYLONITRILE AND ISOPROPANOL, DRAWING THE SPUN FILAMENTS IN A SECOND BATH COMPRISING A SOLVENT FOR THE ACRYLONITRILE AND ISOPROPANOL, CUTTING THE WASHING THE FILAMENTS IN THE RELAXED STATE, IMMERSING THE FILAMENTS IN BOILING WATER WHILE IN A RELAXED STATE, ND DRYING THE FILAMENTS IN A RELAXED STATE. FILAMENTS HAVING A TIGHT REVERSIBLE CRIMP ARE PREPARED.

United States Patent 3,737,504 PROCESS FOR THE PRODUCTION OF CRIMPEDACRYLONITRILE BASE YARNS WITH AN ISO- PROPANOL CONTAINING BATH PaulHerrbach, Lyon, and Alain Breton, Paris, France, assignors toCTA-Compagnie Industrielle de Textiles Artificiels et Synthetiques,Paris, France No Drawing. Filed Apr. 22, 1971, Ser. No. 136,566 Claimspriority, application France, Apr. 24, 1970, 7014955 Int. Cl. D01f 7/00U.s. Cl. 264-168 8 Claims ABSTRACT OF THE DISCLOSURE This inventionrelates to a process for the production of yarns containing at least 50%acrylonitrile having a tight reversible crimp. More particularly, thisinvention relates to a process for the production of yarns and fiberscomprising at least 50% acrylonitrile and having a tight reversiblecrimp suitable for use in knitted and woven goods.

Synthetic yarns and fibers such as polyamides, polyesters, andpolyacrylonitriles may be woven into fabrics having high strength,improved durability, improved launderability, and wrinkle resistance.However, in spite of these superior properties, fabrics produced fromsynthetic yarns, especially those produced from continuous filamentyarns, do not produce products which have asthetic properties similar tonatural yarns. For example, fabrics Woven from such filamentary yarnstend to have a slick, cold hand and often have poor luster and cover. Adesirable synthetic fabric should have a warm, dry hand, good luster andother properties of a naturally occurring wool-type fabric.

Improvements in this area have generally been attained with mixedshrinkage or bicomponent yarns. Although these fibers tend to crimp andloop and give the fabric a greater bulk and cover, the mixed shrinkageor bicomponent yarns often have undesirable physical properties. Theprocessing of acrylonitrile by a wet spinning process, i.e., theextrusion of an acrylonitrile polymer of copolymer base solution into acoagulant bath, although a desirable method for producing acrylonitrileyarns, does not produce yarns with desirable crimp properties.

There have ben many attempts to produce acrylonitrile yarns with a tightreversible crimp directly from the wet spinning process. U.S. Pat.3,447,998 discloses a process for producing self-crimping acrylonitrilefibers utilizing the wet spinning method. However, this process utilizesa coagulating bath which does not appreciably penetrate into the fibers.This creates a fiber with a non-uniform skin, a type of sheath-corerelationship, therefore causing the fibers to crimp and curl. Thisprocess, however, is not suitable for use in producing fibers containingless than 80% acrylonitrile. US. Pat. 3,402,234 discloses a method forobtaining bent fibers by spinning an acrylonitrile polymer solution intoa coagulating bath containing t-butyl or t-amyl' alcohol and a polymersolvent. The polymers produced according to the method of this patent,however, are not self-crimping and also have inferior tensileproperties,

Patented June 5, 1973 such as tenacity and elongation to rupture.Furthermore, in French Pat. 1,385,441 a method is disclosed forpreparing low count vinyl filaments by spinning these polymers into acoagulating bath containing a polymer solvent and a coagulant. However,the process disclosed in this patent also does not produce self-crimpingacrylonitrile filaments.

Briefly, it has been found that inherently self-crimping yarns andfilaments containing at least 50% acrylonitrile are produced byextruding the acrylonitrile base solution into a coagulating bathcontaining a solvent for the acrylonitrile, isopropanol, and between 0and 5% water, drawing the filaments in a second bath containing asolvent for the acrylonitrile, isopropanol and between 0 and 5% water,cutting and washing the filaments in a relaxed state, immersing thefilaments in a relaxed state in boiling water, and drying the filamentsin a relaxed state.

It is, therefore, the primary object of this invention to provide aprocess for the production of acrylonitrile based yarns and filamentshaving a tight reversible crimp.

It is a further object of this invention to provide a process for theproduction of yarns and filaments containing at least 50% acrylonitrilehaving a tight reversible cnmp.

It is a still further object of this invention to provide a process forproducing acrylonitrile yarns and filaments having a tight reversiblecrimp by utilizing the wet spinning process.

-It is yet a further object of this invention to provide a process forproducing acrylonitrile based yarns and filaments having a tightreversible crimp and superior physical properties.

A still further object of this invention is to provide a process forproducing tightly crimped acrylonitrile yarns produced by the wetspinning process utilizing a subsequent treatment bath containingisopropanol.

Still further objects and advantages of the process of the presentinvention will become more apparent from the following more detaileddescription thereof.

The process of the present invention, which is suitable for producingcrimped filaments, fibers, and yarns from solutions of homopolymers,copolymers, and terpolymers containing at least 50% acrylonitrile,comprises: spinning an acrylonitrile based polymer solution, comprisingthe acrylonitrile based polymer dissolved in an organic solvent, into acoagulant bath containing an organic solvent for the acrylonitrilepolymer, isopropanol, and between 0 and 5% water; drawing the spunfilaments in a second bath comprising a solvent for the acrylonitrilepolymer, isopropanol, and between 0 and 5% water; cutting and washingthe filaments in a relaxed state; immersing the filaments in boilingwater in a relaxed state; and drying the filaments in a relaxed state.

The acrylonitrile based polymers suitable for use in the process of thepresent invention include homopolymers of acrylonitrile, mixture ofacrylonitrile polymers with other polymers, copolymers and graftcopolymers containing at least 50% by weight acrylonitrile and less than50% by weight of one or more ethylenically unsaturated monomerscopolymerizable with acrylonitrile, such as vinyl chloride, vinylacetate, vinylidene chloride, acrylic acid, methacrylic acid, esters andamides; methacrylonitrile; compounds containing a carbocyclic acid groupsuch as itacon-ic acid, or a sulphonic acid such as vinylsulphoniccompounds, allyl and methallyl sulfonic acids, sulfonated aromaticcompounds, for example styrenesulphonic acids and vinyl oxyarenesulfonic acids, vinyl derivatives of basic nature such as vinylpyridiueand its alkyl derivatives, vinyl-dialkylamine ethers, etc.

The acrylonitrile polymer is first dissolved in an organic solvent forthe acrylonitrile polymer to form a polymer solution containing from 10to 30% polymer. The

acrylonitrile based polymers can be dissolved in this solvent for theacrylonitrile utilizing any well known technique. Solvents suitable foruse in the process of this invention include dimethylformamide,dimethylacetamide, dimethylsulfoxide, etc. Although the above solventsare preferred, any other solvent which is capable of dissolving theacrylonitrile based polymer may be used in the process of the presentinvention.

This solution of the acrylonitnile based polymer in the organic solventis then extruded into a coagulating bath comprising from 37 to 49% byweight of the solvent for the acrylonitrile based polymer, from 61 to49% by weight of isopropanol, and from to by weight, and preferably from0.1 to 2%, water. The temperature of this coagulating bath is generallykept below 30 C. and preferably between 0 and 20 C.

After leaving the coagulating bath, the filaments thus formed are thendrawn in a bath comprising from 37 to 49% by weight of the solvent forthe acrylonitrile based polymer and from 61 to 49% isopropanol. Althoughthis bath may also contain a small proportion of water, i.e., from 0 to5% water, the water content is preferably from 0.1 to 2% by weight ofwater. The temperature of the drawing bath is preferably between 80 and95 C. Although it is not necessary that the composition of the drawingbath and the coagulating bath be the same, itis generally advantageous,and it is preferred, to utilize a drawing lbath having the samecomposition as the coagulating bath. The rate of drawing in the drawingbath is generally greater than 3X (200%) and preferably between 5x(400%) and X (900%).

Although not necessary for the process of the present invention, thefilaments may be slightly drawn after leaving the coagulating bath andbefore entering the drawing bath at ambient temperature by means of asimple adjustment of the relative speeds of the successive rollerscontrolling the advance of the filaments. These filaments then are drawnin the drawing bath with the composition as defined above such that thetotal draw ratio is greater than 3 X, and preferably between 5 X and10X. Although, as indicated above, the drawing operation may becompleted in a single stage or may be a series of'drawing operations, itis preferable to draw the filaments in a continuous manner following thewet spinning operation.

The high drawing rates at these temperatures are possible because of thedrawing bath composition and this directly contributes to the productionof filaments with improved physical and mechanical properties and inparticular to filaments having a tight reversible crimp, very goodelongation, and a high tenacity.

Following the drawing step, the filaments are cut into fibers in anyconventional manner. The length of these fibers depends entirely upontheir later use, and are generally from 20 to 150 mm. These cut fibersare then washed in water at ambient temperature in at least one vat ortub with the water being passed countercurrent to the direction of thefibers to remove the solvent and isopropanol. The solvent andisopropanol, which is recovered, may be recycled for reuse. The washingstep may also be performed prior to the cutting operation.

The cut and washed fibers are immersed, while in a relaxed state, inboiling water for about 30 seconds in order to develop the crimp and arethen dried by any conventional means, while still in a relaxed state.Alternatively, a thermal treatment may also be employed subsequent todrying utilizing any conventional means in order to further reduceshrinkage of the fibers produced by the present invention.

The fibers produced according to the process of the present inventionhave a tight, stable and reversible crimp and do not require any furthermechanical crimping operations. These fibers also have a good dyeingaifinity and also a good elongation and a high tenacity. These fibersalso are particularly Well suited for producing woven and knittedfabrics.

The process "of the present invention will'be further illustrated bymeans of the following illustrative examples. In the following examples,all parts and percentages are by weight and all temperatures in degreescentigrade. As stated above, these examples are for the purposes ofillustration only and are in no way to be taken as limiting.

EXAMPLE 1 A solution containing 21.5% of a tel-polymer of 92.2%acrylonitrile, 7.2% methyl methacrylate, and 0.6% sodium methallylsulfonate in dimethylformamide' is prepared at 70 C. The specificviscosity of this polymer solution is 0.400 (a 0.2% solution indimethylformamide at 20 C.). This polymer solution is extruded throughaspinneret having 200 holes 0.05 mm. in diameter into a coagulating bathcontaining 2% water, 48% dimethylformamide, and 50% isopropanol, thetemperature of the coagulating bath being 0C. The filaments obtainedfrom this coagulating bath are then drawn in air at ambient temperatureto a draw ratio of 2.90 These filaments are then drawn in a bathcontaining 2% water, 48% dimethylformamide, and 50% isopropanol kept atC.'so as to obtain a total draw ratio of 7.9x. These filaments are thenout into fibers 120 mm. long and washed in a relaxed state in water atambient temperature and flowing countercurrent to the direction oftravel of the fibers. The fibers are then immersed in boiling water in arelaxed state so as to form the crimp. The fibers are then dried in arelaxed state at 70 C. and then subjected to a heat treatment in thepresence of steam at C. Whilein the relaxed state.

The fibers produced according to this process are tested for theircrimping and tensile properties, the individual tests performed and theresults of these tests are summarized in Table I below.

The tests conducted on the fibers include:

Tensile properties.elongati0n to rupture and tensile strength measuredafter treatment, either in the conditioned state, i.e., at 20 C. and 65%humidity, or in the wet state, i.e., after immersion in water.

Crimp properties-level of crimping, frequency of crimping, andpermanence are calculated according to the following formulae:

length of uncrimped fiber length of crimped fiber g h of uncrimped fiberX 100: evel Frequency (crimps/centimeter) X 1/2 Following the procedureof Example 1, the same acrylonitrile solution is extruded into acoagulating bath comprising 2% water, 42% dimethylformamide, and 56%isopropanol, maintained at 0 C. The filaments formed are then drawn in abath containing 2% water, 42% dimethylformamide, and 56% isopropanolmaintained at 88 C. to a draw ratio of 8.8x. These filaments are thencut into fibers mm. long and washed in a relaxed state with water atambient temperature flowing countercurrent with respect to the fibers.These fibers are then im: mersed in boiling water for 30 seconds so asto bring out the self-crimping properties and dried at 70 C.

The tensile and crimping properties measured as indicated in Example 1are as follows:

A dimethylformamide solution containing 23% of a copolymer comprising69% acrylonitrile, 30% vinylidene chloride, and 1% potassiumvinyloxybenzene sulfonate with a specific viscosity of 0.400, (a 0.2%solution of dimethylformamide at 20 C.), is spun into a coagulating bathcomprising 2% water, 38% dimethylformamide, and 60% isopropanol,maintained at 20 C. These filaments are drawn to a draw ratio of 7.9x ina bath with the same composition as the coagulating bath maintained at90 C. These filaments are then processed as in the previous examples andtested in the same manner. The results of these tests are shown in TableIII.

Utilizing the procedure of Example 1 the following acrylonitrilepolymers and copolymers are mixed with enough dimethylformamide to forma 20% solution and these solutions are extruded into a coagulating bathcontaining 2% water, 48% dimethylformamide, and 50% isopropanol,maintained at 0 C. These filaments are also drawn in a drawing bathhaving the same composition as the coagulating bath kept at 90 C. to adraw ratio of 7.9x. After cutting, Washing, and immersing in boilingwater, these fibers are dried at 70 C.

(a) 100% acrylonitrile;

(b) 85% acrylonitrile, methyl methacrylate, 5%

styrene sulfonic acid;

(0) 94% acrylonitrile, 6% vinyl chloride;

(d) 96% acrylonitrile, 4% allyl sulfonic acid;

(e) 52% acrylonitrile, 40% vinylidene chloride, 8% p0- tassiumvinyloxybenzene sulfonate;

(f) 60% acrylonitrile, 25% vinyl acetate, methyl methacrylate;

(g) 92% acrylonitrile, 8% vinylpyridene.

Each of the above compositions when treated according to the process ofthe present invention produces fibers which have excellent crimp leveland frequency and the filaments also have excellent tensile propertiesand count.

EXAMPLE 5 Utilizing the process of Example 1, a solution of a terpolymercontaining 94% acrylonitrile, 5% methyl methacrylate, and 1% potassiumvinyloxybenzene sulfonic acid, in dimethylformamide is extruded into thefollowing coagulant bath compositions:

(a) 2% water, 37%

panol;

dimethylformamide, 61% isoprowater, 49% dimethylformamide, 49%isopropanol; (c) 1% panol; (d) 1% panol; (e) 0% panol; (f) 0% water, 49%

panol.

The fibers are then drawn in a drawing bath having a compositioncorresponding to the individual coagulant bath compositions noted above.After this drawing treatment the filaments are cut and Washed, dried andgiven a heat treatment. Each of these fibers produced has excellentcrimp, count and tensile properties.

EXAMPLE 6 A copolymer of acrylonitrile containing 94% acrylonitrile and6% methyl methacrylate is dissolved in enough of each of the followingorganic solvents to make a 20% solution:

water, 38% dimethylformamide, 60% isoprowater, 49% dimethylformamide,50% isoprowater, 39% dimethylformamide, 61% isoprodimethylformamide, 51%isopro- (a) dimethylformamide; (b) dimethylsulfoxide; (c)dimethylacetamide.

These solutions are then extruded into a coagulant bath containing 2%Water, 48% of the respective solvent shown above, and 5 0% isopropanol.These fibers are then treated in accordance with Example 1, using adrawing bath with a composition corresponding to the composition of thecoagulant bath. The fibers produced have excellent count, tensilestrength and crimp properties.

As can be seen by each of the foregoing examples, the fibers andfilaments produced utilizing the process of the present invention havesuperior crimp properties, and also excellent count and tensileproperties.

While the process of the present invention has been described by way ofthe foregoing specific examples, the process of the present invention isto be in no way limited thereto but is to be construed as broadly as anyand all equivalents of the process as defined in the appended claims.

What we claim is: 1. A process for the production of crimped yarns andfibers from solutions of an acrylonitrile polymer selected fromhomopolymers of acrylonitrile and copolymers of at least 50%acrylonitrile with up to 50% of at least one ethylenically unsaturatedmonomer copolymerizable therewith comprising:

spinning a solution of said acrylonitrile polymer to form filaments,said solution being formed by dissolving said acrylonitrile polymer inacrylonitrile polymer solvent, into a coagulating bath consistingessentially of from 37 to 49% of said solvent, from 61 to 49% ofisopropanol, and from 0 to 2% Water;

drawing the spun filaments to a total draw ratio of from 200 to 900% ina drawing bath consisting essentially of from 37 to 49% of saidacrylonitrile polymer solvent, from 61 to 49% of isopropanol, andbetween 0 and 2% water, said bath maintained at a temperature of from to95 0.;

cutting and washing the drawn filaments while said filaments are in arelaxed state;

immersing the washed and cut filaments in boiling water while saidfilaments are in a relaxed state; and drying the washed and treatedfilaments while in the relaxed state.

2. The process of claim 1 wherein the compositions of the drawing bathand the coagulating bath are substanthe coagulating bath is between 0and 20 C.

6. The process of claim 4 wherein the temperature of 'the coagulatingbath is between 0 and 20C.

7. The process of claim 1 wherein the filaments are drawn prior to thedrawing in the drawing bath. 8. The process of claim 1 wherein thesolvent is dimethylformamide.

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